my loan installment is R1280 and to payments left but my balance is R6563.10

I am disappointed with capitec. I am currently left with two installments on my loan and the balance that they say I'm left with does not match the two installments, its higher. I called 3 times and even went to a branch to find out why my balance is so high. they said they don't know, even their collections department does not know why my balance is higher. so I have a balance that no one can explain.